1. Field of the Invention
The invention relates to an optical touch device and a frame thereof and, more particularly, to a frame, which is adapted for an optical touch device, capable of eliminating background noise well.
2. Description of the Prior Art
Since consumer electronic products have become more and more lighter, thinner, shorter, and smaller, there is no space on these products for containing a conventional input device, such as mouse, keyboard, etc. With development of touch technology, in various kinds of consumer electronic products (e.g. display device, all-in-one device, mobile phone, personal digital assistant (PDA), etc.), a touch device has become a main tool for data input. Compared with other touch design, such as a resistive touch design, a capacitive touch design, an ultrasonic touch design, or a projective touch design, an optical touch design has lower cost and is easier to use.
A conventional optical touch device utilizes light emitting units to emit light onto a touch object (e.g. finger or stylus) such that the touch object reflects light to an image sensing unit. Afterward, the image sensing unit will generate an image after receiving the reflected light. One of the key factors in image processing algorithm is whether the reflected light signal from the touch object can be distinguished from the background noise well. That is to say, if the reflected light signal from the touch object can be distinguished from the background noise well, the image processing algorithm can be processed and controlled well accordingly, otherwise the image processing algorithm may become complicated and has to be calculated by more powerful processor.
In general, the strength of background noise is usually determined according to a frame of the conventional optical touch device. Referring to FIGS. 1 and 2, FIG. 1 is a schematic diagram illustrating a frame 1 of the prior art, and FIG. 2 is a distribution diagram illustrating a signal-to-noise ratio measured by using the frame 1 shown in FIG. 1. As shown in FIG. 1, the frame 1 is formed as a triangular column. As shown in FIG. 2, the background noise is huge and disordered within the signal-to-noise ratio measured by using the frame 1. In other words, the frame 1 cannot eliminate the background noise.